Circadian rhythms allow animals to anticipate daily changes in environmental conditions. The rhythms are produced by the molecular clocks, a set of genes arranged into transcription and translation feedback loop system. Their interaction leads to the generation of transcriptional waves and, as a consequence, rhythmic behaviour and physiology. In Drosophila such molecular clocks are located within the circuitry of neuronal pacemakers. Present research consists of two independent projects. Investigation of TF Unf downstream targets lead to the discovery of a putative regulator of the Wnt-signaling pathway, Rnb, which turned out to have a profound effect on the s-LNvs' molecular clocks as well as the circadian behaviour of the fly. The second part of the work shows that NO, a putative UNF effector, plays roles in both the development of the pacemaker circuitry and generation of locomotor rhythms in Drosophila. Intriguingly, the NO effect is largely mediated by glial cells.